Finland‘s flagship airline Finnair has shut down all flights to and from the Estonian city of Tartu in response to GPS (global position system) issues reported by its planes while cruising near the Russian border.

Russia has been accused of employing GPS jamming tech as early back as 2010, but two flights from Helsinki to Tartu last week reported considerable disturbances prompting the closure of traffic between the two NATO nations.

Plane approaches to Tartu Airport currently rely on GPS signals, said Finnair, which is the only airline to fly into that city.

But there there are other navigational tools that can be used, and the airline said it would suspend daily flights there from April 29 to May 31 so that an alternate solution can be installed at the airport.

Finnair said GPS interference has been increasing over the past two years. “Finnair pilots have reported interference, especially near Kaliningrad, the Black Sea, the Caspian Sea and the Eastern Mediterranean,” the company said.

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Expert Karoliina Ainge, who led Estonia’s cybersecurity policy brief in the past, insisted the Atlantic alliance needs to intervene immediately to stop Russia plunging NATO into a dangerous escalation.

She told Newsweek: “I have no doubts that this will escalate if it receives no response.”

Incidents of GPS jamming have been increasingly reported across countries bordering with Russia since December, with pilots and motorists in Poland warning about a considerable spike.

The practice is relatively easy to carry out as it doesn’t require particularly advanced tech, according to experts at OpsGroup. They also said the use of GPS jamming tech has grown more frequent in conflict zones.

Experts have sought to reassure passengers that the jamming poses no imminent threat to commercial flights as a majority of aircraft are equipped to land without GPS – but Foreign Minister across the Baltic have warned there is a considerable chance of escalation.

Estonian Foreign Minister Margus Tsahkna said Monday that jamming carried out by Russia is so dangerous that sooner or later it will cause a crash, the Baltic News Service said.

“So this is a deliberate action that interferes with our lives lived in a dangerous situation and this can be considered as a hybrid attack,” Tsahkna told Estonian broadcaster ERR.